Dodgeit provides anonymous,
unauthenticated (and thus public) mailboxes for you to use for things
that ask for email addresses, but which you don’t want to give your
own address to, provided that you don’t mind the possibility of the
rest of the world reading that message.

Just in case something useful arrives back at that address, you can
read it on the web — or, better yet, you can subscribe your aggregator
to the RSS
feed associated with the mailbox, and see new mail arrive whenever
you catch up on your feeds.

It also makes a decent voyeur pastime — just guess a name
and read.

I wouldn’t recommend using it for your DynDNS
account though.

(Mailinator did this first, but
their interface is overloaded with things that are not mail (why are
there photos of people taking up so much room?), and they do not offer
RSS reading of mail, which is the killer feature of this sort of
thing for me.)